When serving a karmamudra [spouse], the pure awareness
of bliss and emptiness will arise:
Composed in a blessed union of insight and means,
Slowly send down, retain and draw back up the bodhichitta [the sexual energy],
And conducting it to the source [the divine], saturate the entire body.
But only if lust and attachment are absent will that awareness arise.
Then gaining long-life and eternal youth, waxing like the moon,
Radiant and clear, with the strength of a lion,
You will quickly gain mundane power and supreme enlightenment.
from "The Song of Mahamudra" (Do ha mdzod brgyad ces bya ba Phyag rgya chen po'i man ngag gsal bar ston pa'i gzhung)